The design of a packaged pharmaceutical composition generally seeks to provide an active pharmaceutical ingredient (API) in a suitable package that is convenient to use, that maintains the stability of the API over prolonged storage, and that ultimately allows for the delivery of efficacious, stable, active, nontoxic and nondegraded API.
Most packaged formulations are complex physico-chemical systems, through which the API is subject to deterioration by a variety of chemical, physical, and microbial reactions. Interactions between drugs, adjuvants, containers, and/or closures may occur, which can lead to the inactivation, decomposition and/or degradation of the API.
Historically, glass has been used as the preferred material for packaging pharmaceuticals because of its hermeticity, optical clarity and excellent chemical durability relative to other materials. Specifically, the glass used in pharmaceutical packaging must have adequate chemical durability so as not to affect the stability of the pharmaceutical compositions contained therein. Glasses having suitable chemical durability include those glass compositions within the ASTM standard ‘Type 1B’ glass compositions which have a proven history of chemical durability.
However, use of glass for such applications is limited by the mechanical performance of the glass. Specifically, in the pharmaceutical industry, glass breakage is a safety concern for the end user as the broken package and/or the contents of the package may injure the end user. Further, non-catastrophic breakage (i.e., when the glass cracks but does not break) may cause the contents to lose their sterility which, in turn, may result in costly product recalls.
One approach to improving the mechanical durability of the glass package is to thermally temper the glass package. Thermal tempering strengthens glass by inducing a surface compressive stress during rapid cooling after forming. This technique works well for glass articles with flat geometries (such as windows), glass articles with thicknesses >2 mm, and glass compositions with high thermal expansion. However, pharmaceutical glass packages typically have complex geometries (vial, tubular, ampoule, etc.), thin walls (˜1-1.5 mm), and are produced from low expansion glasses (30-55×10−7K−1) making glass pharmaceutical packages unsuitable for strengthening by thermal tempering.
Chemical tempering also strengthens glass by the introduction of surface compressive stress. The stress is introduced by submerging the article in a molten salt bath. As ions from the glass are replaced by larger ions from the molten salt, a compressive stress is induced in the surface of the glass. The advantage of chemical tempering is that it can be used on complex geometries, thin samples, and is relatively insensitive to the thermal expansion characteristics of the glass substrate. However, glass compositions which exhibit a moderate susceptibility to chemical tempering generally exhibit poor chemical durability and vice-versa.
Finally, glass compositions commonly used in pharmaceutical packages, e.g., Type 1a and Type 1b glass, further suffer from a tendency for the interior surfaces of the pharmaceutical package to shed glass particulates or “delaminate” following exposure to pharmaceutical solutions. Such delamination often destabilizes the active pharmaceutical ingredient (API) present in the solution, thereby rendering the API therapeutically ineffective or unsuitable for therapeutic use.
Delamination has caused the recall of multiple drug products over the last few years (see, for example, Reynolds et al., (2011) BioProcess International 9(11) pp. 52-57). In response to the growing delamination problem, the U.S. Food and Drug Administration (FDA) has issued an advisory indicating that the presence of glass particulate in injectable drugs can pose a risk.
The advisory states that, “[t]here is potential for drugs administered intravenously that contain these fragments to cause embolic, thrombotic and other vascular events; and subcutaneously to the development of foreign body granuloma, local injections site reactions and increased immunogenicity.”
Accordingly, a recognized need exists for alternative glass containers for packaging of pharmaceutical compositions which exhibit a reduced propensity to delaminate.